Actuation device for a control cable for a bicycle gearshift

Abstract

The described actuation device comprises a casing, intended for the attachment to the handlebar of the bicycle, a cable-winding bobbin, angularly mobile in the casing about a main axis of the device, a first driving mechanism, acting on the bobbin to rotate it in a first angular direction, a second driving mechanism, acting on the bobbin to rotate it in a second angular direction opposite the first, as well as indexer assembly for removably holding the bobbin in predetermined angular positions. In accordance with the invention, the indexer assembly comprise first countering member, to counter the rotation of the bobbin in the first direction, and second countering member, distinct from the first countering member, to counter the rotation of the bobbin in the second direction. Asymmetric operation is thus obtained which allows active actuation to be set both for upward gearshifting and for downward gearshifting.

What is claimed is: 
     
       1. Actuation device for a control cable for a bicycle gearshift, comprising:
 a housing, attachable to a bicycle handlebar, 
 a cable-winding bobbin, angularly mobile in the housing about a main axis of the device, 
 a first driving mechanism, acting on the bobbin to rotate the bobbin in a first angular direction, 
 a second driving mechanism, acting on the bobbin to rotate the bobbin in a second angular direction opposite the first angular direction, 
 an indexer assembly to removably hold the bobbin in predetermined angular positions, 
 wherein said indexer assembly comprises: 
 a first biased countering member, to counter the rotation of the bobbin in the first angular direction, 
 a second biased countering member, distinct from the first biased countering member, to counter the rotation of the bobbin in the second angular direction, and 
 at least two directly opposed discs that have a substantially identical diameter and are assembled together, 
 wherein one of the at least two opposed discs has a plurality of recesses that are dimensioned to releasably receive a stop member that is limited during the stop member's movement to travel within a radially outwardly extending groove that is formed in an other one of the at least two opposed discs that are assembled together, 
 the first biased countering member is arranged in the radially outwardly extending groove and the radially outwardly extending groove limits movement of the first biased countering member, and 
 the stop member is biased towards said plurality of recesses for direct engagement with a respective one of the plurality of recesses. 
 
     
     
       2. The device of  claim 1 , wherein the first biased countering member counters the rotation of the bobbin in a different direction than the second biased countering member. 
     
     
       3. The device of  claim 1 , wherein the first and/or the second biased countering member counters the rotation of the bobbin independently of the angular position of the bobbin. 
     
     
       4. A bicycle gearshift actuator comprising:
 a) a housing configured for attachment to a bicycle handlebar; 
 b) a shaft that is carried by the housing; 
 c) a shank having a central opening and opposed flat faces; 
 d) a bobbin that has a central opening mounted adjacent the shank and defines a connection point for a gear shift cable, the bobbin and shank are positioned for rotation about the shaft; 
 e) a first lever operatively connected to the shank and bobbin and rotating the shank and bobbin in a first direction; 
 f) a second lever operatively connected to the shank and bobbin and rotating the shank and bobbin in a second direction; and 
 g) an indexer assembly having a first biased control portion that limits the rotation of the bobbin in the first direction, a second biased control portion that limits the rotation of the bobbin in the second direction, and 
 an indexing disc and a ball-carrying disc that have a substantially identical diameter and are directly opposed to one another, 
 wherein the indexing disc has a plurality of recesses that are dimensioned to releasably receive a stop member that is limited during the stop member's movement to travel within a radially outwardly extending groove that is formed in the ball-carrying disc, 
 the first biased control portion is arranged in the radially outwardly extending groove and the radially outwardly extending groove limits movement of the first biased control portion, and 
 the stop member is biased towards said plurality of recesses for direct engagement with a respective one of the plurality of recesses. 
 
     
     
       5. The actuator of  claim 4 , wherein the stop member comprises at least one ball, the indexing disc comprises a stationary member integral with the housing, and the ball-carrying disc comprises a rotating member integral in rotation with the bobbin, and the at least one ball is engaged both with the stationary member integral with the housing and with the rotating member integral in rotation with the bobbin;
 the first biased control portion comprises a first countering spring that acts on the ball to keep the ball in a stop position; and 
 the second biased control portion comprises a second countering spring that acts upon the ball to keep the ball in the stop position. 
 
     
     
       6. The actuator of  claim 5 , wherein a rotation of the bobbin in a first angular direction biases the at least one ball away from the stop position, in contrast to the first countering spring. 
     
     
       7. The actuator of  claim 5 , wherein a rotation of the bobbin in a second angular direction biases the at least one ball away from the stop position, in contrast to the second countering spring. 
     
     
       8. The actuator of  claim 5 , wherein the ball-carrying disc is mounted in the housing and the at least one ball is mounted in the radially outwardly extending groove so that the at least one ball is thrusted radially outwards by the first countering spring, the radially outwardly extending groove being open on at least one side of the ball-carrying disc and having a depth such that the at least one ball projects in the axial direction from the ball-carrying disc;
 the indexing disc is mounted in the housing in an interfacing position adjacent to the ball-carrying disc, facing the at least one side of the ball-carrying disc from which the at least one ball projects, and the plurality of recesses are arranged according to a pattern that comprises stop zones and sliding zones alternating with each other; 
 the second countering spring is mounted in the housing so as to axially bias the indexing disc and the ball-carrying disc one against the other; 
 the at least one ball, projecting axially from the radially outwardly extending groove on the ball-carrying disc, is engaged in the recess on the indexing disc. 
 
     
     
       9. The actuator of  claim 8 , wherein an intermediate of the stop zones is defined by a stop wall orientated according to a stop direction and by a sliding wall orientated according to a sliding direction, the stop direction and sliding direction of each of the stop zones defining an acute angle that does not enclose the main axis of the device. 
     
     
       10. The actuator of  claim 9 , wherein the stop walls are fitted to the sliding walls in a succession that forms an outer peripheral margin of the recess on the indexing disc. 
     
     
       11. The actuator of  claim 10  wherein the recess on the indexing disc is defined towards the inside by an inner peripheral margin corresponding to the outer peripheral margin. 
     
     
       12. The actuator of  claim 10  wherein the recess on the indexing disc is not defined towards the inside by any inner peripheral margin. 
     
     
       13. Device according to  claim 8 , wherein the groove in the ball carrying disc is open on both sides of such a disc and has a depth such that the ball projects in the axial direction from the ball-carrying disc, from both sides thereof; wherein
 the indexer assembly also comprises a second indexing disc integral in rotation with the first indexing disc, mounted in the housing in an interfacing position adjacent to the ball-carrying disc on the opposite side with respect to the first indexing disc and provided with a recess specularly corresponding to that of the first indexing disc; and wherein 
 the ball, projecting axially from the groove on the ball-carrying disc, is engaged both in the recess on the first indexing disc, and in the recess on the second indexing disc. 
 
     
     
       14. The actuator of  claim 8 , wherein the stationary member comprises the ball-carrying disc and the rotating member comprises the first indexing disc. 
     
     
       15. The actuator of  claim 5 , wherein the indexer assembly comprises a further ball, engaged both with the stationary member and with the rotating member. 
     
     
       16. The actuator of  claim 15 , wherein the indexer assembly includes a further first countering spring that acts upon the further ball to keep the further ball in a stop position. 
     
     
       17. The actuator of  claim 16 , wherein a rotation of the bobbin in the first angular direction biases the further ball against an associated first countering spring away from the stop position. 
     
     
       18. The actuator of  claim 16 , wherein a rotation of the bobbin in the second angular direction biases the further ball against the second countering spring away from the stop position. 
     
     
       19. The actuator of  claim 15 , wherein:
 the ball-carrying disc is mounted in the housing, and the radially outwardly extending groove includes at least two radially outwardly extending grooves, in each of said at least two radially outwardly extending grooves being mounted one of said balls so that each ball is thrusted radially outwards by a respective one of the first countering spring or a further first countering spring, the at least two radially outwardly extending grooves being open on at least one side of the ball-carrying disc and having a depth such that the balls project in the axial direction from the ball-carrying disc; 
 the indexing disc is mounted in the housing in an interfacing position adjacent to the ball-carrying disc, facing the at least one side of the ball-carrying disc from which the balls project, the plurality of recesses have identical profiles and are arranged according to patterns that comprise stop zones and sliding zones alternating with each other; and wherein: 
 the second countering spring is mounted in the housing so as to axially bias the indexing disc and the ball-carrying disc one against the other; 
 the balls, projecting axially from the at least two radially outwardly extending grooves on the ball-carrying disc, are respectively engaged in the two recesses on the indexing disc. 
 
     
     
       20. The actuator of  claim 19 , wherein an intermediate of the stop zones is defined by a stop wall orientated according to a stop direction and by a sliding wall orientated according to a sliding direction, the stop direction and sliding direction of each of the stop zones defining an acute angle that does not enclose the main axis of the device. 
     
     
       21. The actuator of  claim 20 , wherein the stop walls are fitted to the sliding walls in a succession that forms an outer peripheral margin of the recesses on the indexing disc. 
     
     
       22. The actuator of  claim 21 , wherein the recess on the indexing disc is defined towards the inside by an inner peripheral margin corresponding to the outer peripheral margin. 
     
     
       23. The actuator of  claim 21 , wherein the recesses on the indexing disc are not defined towards an inner radial direction by any inner peripheral margin. 
     
     
       24. The actuator of  claim 19 , wherein:
 the grooves in the ball-carrying disc are open on both sides of such a disc and have a depth such that the balls project in the axial direction from the ball-carrying disc, from both sides thereof; wherein 
 the indexer assembly also comprises a second indexing disc integral in rotation with the first indexing disc, mounted in the housing in an interfacing position adjacent to the ball-carrying disc on the opposite side with respect to the first indexing disc and provided with a recess specularly corresponding to that of the first indexing disc; and wherein 
 the balls, projecting axially from the grooves on the ball-carrying disc, are engaged both in the recess on the first indexing disc, and in the recess on the second indexing disc. 
 
     
     
       25. The actuator of  claim 19 , wherein the stationary member comprises the ball-carrying disc and the rotating member comprises the first indexing disc. 
     
     
       26. The actuator of  claim 5 , wherein the first countering spring is a helical spring compressed between the ball and an abutment on the ball-carrying disc. 
     
     
       27. The actuator of  claim 8 , wherein the first countering spring is a flat spring mounted on the ball-carrying disc and acting on the ball. 
     
     
       28. The actuator of  claim 8 , wherein the first countering spring is a single flat spring mounted on the ball-carrying disc and acting on the two balls. 
     
     
       29. The actuator of  claim 8 , wherein the second countering spring is a Belleville washer, arranged coaxially to the ball-carrying disc and to the indexing disc. 
     
     
       30. The actuator of  claim 8 , wherein the second countering spring is an elastically deformable elastomeric ring, arranged coaxially to the ball-carrying disc and to the indexing disc. 
     
     
       31. The actuator of  claim 5 , wherein the first countering spring applies on the ball or on the balls a force in the radial direction that is less than 1/20  of the force that the second countering spring applies on the ball or on the balls in the axial direction.